1. Field of the Invention
This invention relates to a storage system connected in a loop to a plurality of magnetic disks or other physical disks, and a disconnecting method of faulty storage device. In particular, this invention relates to a storage system and faulty storage device disconnecting method in which a faulty storage device in a loop is disconnected and bypassed.
2. Description of the Related Art
In a storage device that uses magnetic disks, magneto-optical disks, optical disks, or other storage media, the storage media is actually accessed at the request of a data processing device. When the data processing device uses a large volume of data, a storage system having a plurality of storage devices and control devices is employed.
In such a storage system, a redundant configuration is adopted in order to improve the reliability of stored data and device reliability, and a FC_AL (Fiber Channel Arbitrated Loop) interface is used for rapid data transfer. Numerous storage devices are connected to this FC_AL loop. Because of this, when a malfunction occurs in a storage device in the loop, the entire loop is affected. Consequently, technology to disconnect a malfunctioning storage device from the loop, and to eliminate the effect on the loop as a whole, is necessary.
In the prior art, two methods of disconnecting a malfunctioning storage device (magnetic disk device) from an FC_AL loop are known. FIG. 19 is a drawing that explains the first of these conventional technologies.
As shown in FIG. 19, each of the plurality of magnetic disk devices 160, 162, 164 is connected by fiber switches 130 to 134 and 140 to 144 to the pair of fiber channel loops 106 and 108. The fiber channel loop 106 is connected to the controller device adapter 102 by the fiber channel connector 114; the fiber channel loop 108 is connected to the controller device adapter 104 by the fiber channel connector 116.
Both device adapters 102, 104 are connected to the central control module 100 of the controller. Hence the central control module 100 can access each of the magnetic disk devices 160, 162, 164, using both one route (route a) via the device adapter 102 and fiber channel loop 106, and another route (route b) via the device adapter 104 and fiber channel loop 108.
A disconnecting control portion 150 and 152 are provided in each of the fiber channel loops 106, 108. The disconnect control portion 150 controls disconnect (bypassing) of each of the fiber switches 130, 132 and 134 of the fiber channel loop 106; the disconnect control portion 152 controls disconnect (bypassing) of each of the fiber switches 140, 142 and 144 of the fiber channel loop 108.
For example, as shown in FIG. 19, when the magnetic disk device 162 cannot be accessed via port a on the side of the fiber channel loop 106, a disconnect command is transmitted to the disconnect control portion 150 from port b on the side of the fiber channel loop 108, via the magnetic disk device 162.
By this means, the disconnect control portion 150 switches the fiber switch 132 on the side of port a of the magnetic disk device 162 to the bypass state as shown in FIG. 19, and disconnects the magnetic disk device 162 from the fiber channel loop 106. Thus the fiber channel loop 106 functions normally, and the magnetic disk device 162 can be accessed from port b on the side of the fiber channel loop 108.
FIG. 20 is a drawing which explains the second conventional technology. Similarly to FIG. 19, the central control module 100 accesses each of the magnetic disk devices 160, 162 and 164 by both one route (route a) via the device adapter 102 and the device channel loop 106, and by another route (route b) via the device adapter 104 and the fiber channel loop 108.
Switch control lines 118 and 120 are built on each of the fiber channel loops 106, 108, from each device adapter 102, 104, and each of the fiber switches 130 to 134 and 140 to 144 of the fiber channel loops 106 and 108 is controlled from the device adapters 102, 104 (for example, Japanese Patent Laid-open No. 2001-306292).
For example, as shown in FIG. 20, when port a on the side of the fiber channel loop 106 of the magnetic disk device 162 cannot be accessed, the fiber switch 132 on the port a side of the magnetic disk device 162 is switched to the bypass state as shown in FIG. 20 from the device adapter 102 via the switch control line 118, so that the magnetic disk device 162 is disconnected from the fiber channel loop 106. By this means, the fiber channel loop 106 functions normally, and the magnetic disk device 162 can be accessed from port b on the side of the fiber channel loop 108.
In case of the first conventional technology, when only one of the ports (for example, port a) is faulty as in FIG. 19, the one port (port a) of the magnetic disk device can be disconnected; but when both ports (port a and port b) are faulty, both ports cannot be disconnected, and so both fiber channel loops 106 and 108 can no longer operate, so that a system shutdown occurs.
In the case of the second conventional technology, so long as the switch control lines 118 and 120 are functioning normally, as shown in FIG. 20, any arbitrary faulty port can be disconnected; but if there is an abnormality (for example, a line break) in the switch connection lines 118, 120, none of the ports can be disconnected, the fiber channel loops 106, 108 can no longer operate, and a system shutdown may occur. Further, when the switch control lines 118, 120 are also being used as low-speed buses or for other uses, disconnect control requires time.